1. Field of the Invention
This invention relates to a trailer, and in particular to a trailer having at least two axles and of a type suitable for carrying heavy loads over rough terrain. The invention is particularly applicable to four-wheeled close-coupled trailers. The four-wheeled configuration has the advantage that the trailer can be free-standing even when part loaded, and also facilitates hitching to a towing vehicle.
2. Description of the Prior Art
Conventional trailers adapted to be towed by motor vehicles are generally secured to the towing vehicle by means of a rigid tow bar, which may be an integral extension of the trailer chassis. The attachment to the towing vehicle, which is generally by means of a metal ring integral with the tow bar and secured by a hook or pin to a bracket on the towing vehicle. This, in combination with the designed length of the tow bar, allows a useful degree of articulation, especially with a tracked towing vehicle such as the M109 SP Howitzer.
When a trailer is being towed over rough cross-country terrain, particularly at speed, rolling and pitching movements of the trailer put considerable stresses on the tow eye unit, causing deformations, cracks and, eventually, fractures.
This occurs because the tow bar cannot move up or down relative to the trailer and the trailer and its load exert a considerable, if transitory, torque on the tow bar.
German Patent Application No. 2,454,010 discloses a tow bar having forward and rear sections, the forward section being pivotable upwards relative to the rear section, about a horizontal axis, to accommodate sudden upward movements of the towing vehicle. The front section has a rearward extension beyond the pivoting axis and above the rear section, and a vertically extending compression spring, positioned between the said rearward extension and the rear tow bar section, opposes the upward pivoting movement.